This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We propose to study the organization of segrosome, the cellular apparatus for chromosome segregation in human pathogen Mycobacterium tuberculosis. Two proteins (ParA and ParB) and a set of original-proximal DNA sequences (parS) form the segrosome machinery. ParA is a motor protein that drives this process. ParB forms a nucleo-protein complex with the parS DNA sequence and polymerize on the parS-proximal DNA scaffold to form a superstructure. Our aim is to elucidate the three-dimensional organization of this nucleoprotein complex for the segrosome of M. tuberculosis. X-ray solution scattering data (SAXS) obtained from SSRL will be combined with additional experimental data and homology modeling approach to build a model of the ParB-parS complex and the nucleoprotein filament.